This invention relates to a quartz crystal vibrator and, more particularly, to a quartz crystal vibrator of the type in which a plate-shaped quartz crystal vibrator element, having electrodes formed thereon, is received in a holding case.
Quartz crystal vibrators deliver very stable oscillation frequencies and therefore are employed widely as oscillators to produce clock signals in computers or in electronic timepieces. According to the basic construction of quartz crystal vibrators of the foregoing type, a quartz crystal vibrator element, such as a circular plate-shaped AT-cut quartz crystal having electrodes formed on both sides thereof, is sealed hermetically in a metal holding case, with the electrodes of the vibrator being led out from the holding case by means of external terminal pins connected to the electrodes within the case. The method of manufacture is as follows. First, an AT-cut quartz crystal element which is circular or rectangular in shape, is prepared, and both sides of the crystal are polished. These sides may be polished to mirror surfaces if required. Next, each side of the crystal is provided with a circular or elliptical excitation electrode, as well as with a connecting conductor which is extended from the excitation electrode to the circumference of the crystal along the surface thereof. This furnishes the complete quartz crystal vibrator element. A metal base member is also provided. The base member is pierced by two external terminal pins which are hermetically and electrically insulated with respect to the base member. Next, the upper ends of the terminal pins are rounded into a ring-like configuration to form clips. The circumferential portions of the connecting conductors on both sides of the quartz crystal vibrator element are clamped between the clips, and an electrically conductive adhesive is applied to the portions where the clamping is effected. Thus, when the adhesive hardens, the quartz crystal vibrator element will be fixedly secured to the terminal pins. The quartz crystal vibrator element is then covered with a mask having windows at the portions thereof that confront the excitation electrodes on the vibrator element. During actual vibration of the vibrator element in an oscillator, a thin metallic film is vapor deposited on the excitation electrode through the corresponding windows of the mask, thereby to adjust the oscillation frequency to a desired value. Finally, the mask is removed, the vibrator element is covered with a metal cap, and nitrogen is sealed within the space enclosed by the cap.
Problems are encountered in the conventional quartz crystal vibrator described above when the vibrator element is clamped between the clips provided at the ends of the terminal pins. Specifically, it is required that the vibrator element be so positioned as to bring the connecting conductors on both sides thereof into position opposite the clips, and it is required also that the frequency adjusting mask be attached and detached. These operations are laborious and time consuming and therefore not only diminish the efficiency of the assemblage operation but also make it impossible to realize assemblage in a fully automatic manner.